The desire to dominate can take a weird turn if using your anti-gravity guns reveals them and makes it likely others will soon invent the same. There is precedent for this, say in electronic warfare or cyberwarfare. As soon as you reveal your uber virus, anyone can take it apart and modify it for their own purposes. So you don't reveal it except as a last resort. Competition doesn't come into play then, everyone hides their secret weapons and never uses them unless they have to, and tries to make sure information in that area is suppressed. However, as I say in other comments, this may have been a bottom up conspiracy, not a top down conspiracy, though it may have moved to the top as the scientists themselves gained power. But the fear would still exist at all levels; sure your anti-gravity gun gives you an advantage, but what if it eventually causes random micro black holes to appear near where you use it, obliterating infrastructure before evaporating? We just don't know what the repercussions of new technologies will be, and while the risks have seemed low in areas like software, the risks seem higher with fundamental new physics. People are historically pretty bad at predicting how technology/science will play out in the long term. AI was a joke for a long time, until it wasn't. The internet was hailed as revolutionary, but it seems very different than it did in the year 2000. It's a lot like computer security, you can imagine the possibilities, but you probably can't imagine ALL the possibilities. It takes time and collaboration to scope out what it is that is new that can now be accomplished. That uncertainty scares some people and excites others. Seems kind of like walking through a minefield littered with Christmas presents. Some people might decide to leave the presents where they are.